AC belt
 

So basically, in the high rpms (or long enough in mid-range) I hear a chirping sound from the engine bay. It's only when the AC is on so it either is the belt or an issue with the compressor itself. Assuming it is the belt, does it need to be replaced or should I just be able to tighten it? Not sure off the top of my head exactly when I replaced it, but I had the AP pulley installed at around 10,000 miles I believe so it's been there for around 20k miles. The belt shouldnt be bad that soon, right?

that really depends

if you over tighten it, the belt's life will be significantly shorter, if its WAY too tight, it might actually damage the pulley that its connected to.

Most people does not have the tension tool. so to check the tension, You have to do it in the old fashion way. just try to twist the belt by around a quarter turn with ur hands. if u can go over quarter turn, u need to tighten it a bit more. if u can barely turn the belt, its way too tight.

Find the balance in between, adjust it. run the car for an hour or so, if it squeak, check the belt again.

oh also, if u notice ANY cracks on the thread of the belt, replace it.

I heard tightening a belt, using it, then swapping pulleys and stuff and trying to use the belt again can sometimes result in noise too. It might not be as happy.

There are two belts, they run somewhere around $12 each (one costs a little bit more than the other). If in doubt, swap it. You can buy them at just about any auto store.

True that, belts are cheap anywayz ~ (compare to the related parts)